Following in the footsteps of former Red Sox outfielder Johnny Damon and his 2006 dash to the rival Yankees, former Celtics guard Ray Allen at least temporarily wiped away five years of goodwill Friday night when he took less money to sign with the rival Miami Heat.

The man affectionately known as Jesus Shuttlesworth will be branded a traitor after taking half the paycheck to chase another title with the world champs, rather than try to topple the East's new juggernaut with his Big Three brethren.

When Allen returned from Miami without giving a formal decision to the Heat brass about his future, many Boston supporters took it as an encouraging sign that loyalty, and a bigger payday, would win out.

As Celtics coach Doc Rivers said last week, the idea of Allen in a Heat jersey was practically unfathomable.

But Allen became the latest to take his talents to South Beach on Friday night, and Heat owner Micky Arison alerted the world as he subtly bragged about the acquisition on Twitter. Arison might want to send one of his cruise ships to squire Allen out of town, as a throng of green-dipped pitchforks are probably standing outside his gates in Wellesley.

It's going to take a while for most Celtics fans to be able to swallow this news.

There will come a time, maybe even as soon as Allen's first visit to TD Garden next season, when those Boston fans will be able to stomach the sight of what had previously been just a LeBron James-retweeted photoshop of Allen in a No. 20 Heat jersey.

Eventually, fans will reflect fondly on Allen's contributions and remember that he was the first domino to fall in place for Boston's new Big Three (well, besides those pesky pingpong balls that went the wrong way). If the Celtics hadn't traded for him on draft night in 2007, it's unlikely Kevin Garnett would have ever arrived to round out the Big Three.

It's safe to say that no one in Boston is smiling about Ray Allen's move to Miami. ESPN.com Illustration

Allen aided a championship season in 2007-08, as well as a run to the cusp of another in 2010. He quietly averaged 16.7 points per game and twice set the Celtics' team record for 3-point percentage in a season. Last year, he became the NBA's all-time leader in trifectas while wearing a Boston uniform.

Over the last two seasons, Allen took a discount to return to Boston in 2010, endured constant trade chatter at the last two deadlines, and lost his starting job last season while battling bone spurs in his ankle that hindered him late in the year and into the postseason.

None of that really matters to Boston fans at the moment. The bottom line is that Allen is joining forces with a bitter rival, one that has knocked the Celtics out of the postseason in each of the last two seasons, and Boston fans are downright angry.

About the only thing worse would have been Allen landing in a Lakers jersey. Even then, their paths would have crossed only twice per season. The Celtics and Heat meet four times each year and have jousted in the playoffs each of the last three seasons.

Next year's postseason showdown seems inevitable, and it's likely that none of the luster of Allen going up against his old team will be lost during four regular-season meetings.

But Allen's decision only further spices up a budding rivalry. The Celtics spent the last week putting much of their 2011-12 roster back together with the idea of making another charge at the Heat.

Miami spoiled the party, wooing Allen away on the sales pitch of Pat Riley (along with James and Dwyane Wade). Oh sure, you can totally understand why Allen would be lured by the glitz and glamour of South Beach. The golf clubs don't go into hibernation in the winter, and with a Big Three of their own -- James, Wade and Chris Bosh -- Miami is positioned to be a perennial contender moving forward.

Allen might not have a definitive role with the Heat quite yet -- heck, he didn't in Boston, either, with the offseason addition of Jason Terry -- but we saw in the postseason how 3-point threats like Mike Miller and Shane Battier benefited from clean looks as James and Wade attacked the basket. Even with a diminished ability to generate his own shot as he prepares to turn 37 and comes off ankle surgery, you can envision Allen bouncing back next year because of the open shots he'll enjoy as part of Miami's offense.

As much sense as the move made, Celtics fans don't want to hear any of it.

Boston was positioned to offer a two-year, $12 million contract that would have paid Allen twice the annual salary that Miami offered. But money clearly wasn't the biggest incentive here for Allen.

The feeling of being wanted probably was near the top of his wish list, and Miami made Allen its biggest offseason priority. Boston maintained a strong desire to have Allen back next season, but put far more energy into bringing back Garnett and Brandon Bass, along with lining up deals with Terry and Jeff Green. It's somewhat remarkable that Garnett, Bass and Terry are all looking at three-year deals (and Green's might be even longer), but the Celtics offered only a two-year pact for Allen.

Allen almost certainly felt as though Miami was pulling the rope harder in this two-team tug-of-war. The Celtics wanted him; the Heat wanted him more.

What can we learn from Damon's time in New York? It took three years, but he got his elusive second title with the Yankees in 2009 -- though not before the Red Sox got their second in 2007. Celtics fans are hoping that Pierce and Garnett get to hoist the Larry O'Brien trophy again before Allen and his new teammates do.

The Celtics are hoping to make Allen regret his decision. That might be the only way the sting from his decision Friday could ever truly dissolve for most Boston fans.